I have just had a quick play with your shot and there is no doubt that you can lighten things up very significantly in such a way that I believe the shot is improved - either by lightening the midtones in 'levels' or using the curve. Now whether this would then lead to an acceptance is a different matter .

I think you would then need to reassess the overall quality issues, but I would say that the screener may have been thinking that the shot (as it is) is looking unnecessarily dark - i.e. it could be improved further in editing without compromising the contrast.

I played around with it in photoshop and it's a tough balance. Brightening the plane means blowing out the background and losing some of the depth in the clouds, also giving the impression that the subject is backlit slightly. This is the best I could come up with. Maybe still a little dark?